Mechanical degradation of dilute polymer solutions under turbulent flow

Kim, C.A; Kim, J.T; Lee, K; Choi, Hyoung Jin; Jhon, Myung S.

doi:10.1016/s0032-3861(00)00135-x

Cited by 78 publications

(43 citation statements)

References 23 publications

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“…1 suggests that plotting the quantity 2 L 2 ͞4d 2 ln(L͞a) vs. the Re of the flow will reduce the anomalous scission data of Fig. 1 and other scission data (13,30,33,34) generated in turbulent flows (listed in Table 1) to a master curve for a given polymer. The range of the Fig.…”

Section: Resultsmentioning

confidence: 99%

Universal scaling for polymer chain scission in turbulence

Vanapalli¹,

Ceccio

Solomon

2006

Proc. Natl. Acad. Sci. U.S.A.

105

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We report that previous polymer chain scission experiments in strong flows, long analyzed according to accepted laminar flow scission theories, were in fact affected by turbulence. We reconcile existing anomalies between theory and experiment with the hypothesis that the local stress at the Kolmogorov scale generates the molecular tension leading to polymer covalent bond breakage. The hypothesis yields a universal scaling for polymer scission in turbulent flows. This surprising reassessment of over 40 years of experimental data simplifies the theoretical picture of polymer dynamics leading to scission and allows control of scission in commercial polymers and genomic DNA.bond breakage ͉ drag reduction ͉ polymer dynamics ͉ Kolmogorov cascade ͉ DNA rupture L ong-chain polymers undergo scission in strong flows because of the coupling of continuum-scale mechanical and atomicscale chemical processes (1, 2). The interactions that connect these disparate scales are poorly understood. Yet, practically, polymer chain scission is a principal determinant of the performance of operations in many fields, including turbulent drag reduction for pipelines and ships (3), microfluidic handling of polymeric fluids (4), and gene therapy using plasmid DNA (5). Alternatively, chain scission underlies technologies such as the shotgun sequencing of DNA (6) and the generation of monodisperse polymer standards (7). The design and control of polymer scission in each of these flows is driven by the scaling relationship between the strength of the flow, as quantified by the fluid strain rate, and the scission product distribution, as quantified by the molar mass of ruptured polymer chains. Since Frenkel (8) published the first treatise on polymer chain scission more than 60 years ago, this fundamental issue has remained unresolved.Scission theories for laminar flow hypothesize that the drag force, F d , experienced by the chain induces a tension that breaks the molecule if it is greater than the critical strength of a polymer covalent bond. In a purely extensional flow, for example, the maximum tension is at the midpoint (9). If the extended chain is modeled as a slender rod, then the tension induced by the drag is F d ϳ VR ϳ R 2 (10). Here is the solvent viscosity, V is the relative velocity of the solvent flowing past the rod at its half-length R and is the macroscopic fluid strain rate (ϳV͞R). Two laminar theories identify different regimes depending on the ratio of polymer relaxation time to flow residence time, the Deborah number (De). For the De Ͻ Ͻ 1 regime, such as in stagnation point flow of a cross-slot, chains are fully stretched such that R ϳ O(L), where L is the contour length of the chain (10). For the De Ͼ Ͼ 1 regime, such as in transient extensional flows generated in contraction-expansion geometries, chains adopt only a partially stretched conformation and R ϳ O(R g ), where R g is the radius of gyration (11). These viscous flow models yield distinct scaling relationships: c ϳ L Ϫ2 for De Ͻ Ͻ 1 and c ϳ L Ϫ1 for De Ͼ Ͼ 1, whe...

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Section: Resultsmentioning

confidence: 99%

Universal scaling for polymer chain scission in turbulence

Vanapalli¹,

Ceccio

Solomon

2006

Proc. Natl. Acad. Sci. U.S.A.

105

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“…One common problem with drag reducing polymers is that the drag reducing effectiveness diminishes significantly when exposed to turbulent flow fields for an extended period of time [5,6]. One explanation for the decreased effectiveness is that, under the stresses of a turbulent flow, the polymer molecules fracture.…”

Section: Introductionmentioning

confidence: 99%

Drag reduction effectiveness of dilute and entangled xanthan in turbulent pipe flow

Wyatt

Gunther

Liberatore

2011

Journal of Non-Newtonian Fluid Mechanics

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“…The effect of different solvents (benzene, chloroform and toluene) on turbulent DR and mechanical degradation of polystyrene using RDA was investigated by Kim et al [46]. DR efficiency was observed to decrease as a function of time, due to polymer degradation.…”

Section: Experimental Work Related To Polymer-induced Turbulent Drmentioning

confidence: 99%

Reviews on drag reducing polymers

Tiong

Perumal

2015

Korean J. Chem. Eng.

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Polymers are effective drag reducers owing to their ability to suppress the formation of turbulent eddies at low concentrations. Existing drag reduction methods can be generally classified into additive and non-additive techniques. The polymer additive based method is categorized under additive techniques. Other drag reducing additives are fibers and surfactants. Non-additive techniques are associated with the applications of different types of surfaces: riblets, dimples, oscillating walls, compliant surfaces and microbubbles. This review focuses on experimental and computational fluid dynamics (CFD) modeling studies on polymer-induced drag reduction in turbulent regimes. Other drag reduction methods are briefly addressed and compared to polymer-induced drag reduction. This paper also reports on the effects of polymer additives on the heat transfer performances in laminar regime. Knowledge gaps and potential research areas are identified. It is envisaged that polymer additives may be a promising solution in addressing the current limitations of nanofluid heat transfer applications.

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Mechanical degradation of dilute polymer solutions under turbulent flow

Cited by 78 publications

References 23 publications

Universal scaling for polymer chain scission in turbulence

Universal scaling for polymer chain scission in turbulence

Drag reduction effectiveness of dilute and entangled xanthan in turbulent pipe flow

Reviews on drag reducing polymers

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